Introduction to Animal Welfare and the Sheep

Effects of Birth Weight on Animal Performance, Fattening Traits and Meat Quality of Lambs

Simple Summary

It is accepted that a low body weight at birth (<4 kg) might impair postnatal muscle and increase adipose tissue development during the whole life of lambs. Therefore, in the present study, we aimed to evaluate the effect of body weight at birth of lambs on the growth performance, ruminal parameters, digestibility, non-carcass components, carcass traits, physicochemical characteristics and fatty acid profile of meat when slaughtered at 27 kg. Compared to the lambs born with a high weight (>5.5 kg), the lambs born with a low body weight showed a worse animal performance during the fattening period, and increased fat depots with a higher content of saturated fatty acids and a reduced tenderness of meat.

Abstract

Intrauterine growth restriction (IUGR) is a key developmental programming factor which might impair both the feed efficiency of lambs and meat quality, since it deeply impacts skeletal muscle and adipose tissue development. To determine the effect of birth weight on the growth performance, ruminal parameters, digestibility, non-carcass components, carcass traits, physicochemical characteristics and fatty acid profile of meat, two experimental groups (six animals in each group) of male Merino lambs with different body weights (BW) at birth (low BW (LW; 3.88 ± 0.281 kg) and high BW (HW; 5.80 ± 0.647 kg)) were used. The lambs were penned with their corresponding ewe during the natural suckling period, being weaned at 15 kg. Then, the lambs were penned individually and offered a complete pelleted diet during the fattening period. All the animals were slaughtered when they reached 27 kg of BW. After weaning, both daily dry matter intake (578 vs. 615 g/day; p = 0.021) and average daily gain (141 vs. 190 g/day; p = 0.004) were significantly lower in LW lambs, and a higher feed:gain ratio was recorded for this group (3.98 vs. 3.45; p = 0.008). Carcass traits did not show differences (p > 0.05) between both groups of lambs, except for higher chilling losses for the LW group (3.29 vs. 2.69%; p = 0.012). Additionally, higher amounts of kidney knob and channel fat were observed for LW lambs (85.4 vs. 152 g; p = 0.028). Apart from a higher hardness of meat in LW lambs (152 vs. 189 Newtons, p = 0.040), no other differences (p > 0.05) were observed in the physicochemical traits of this product; however, the meat of LW lambs tended (p = 0.057) to contain more total fatty acid content with a higher (p = 0.041) proportion of saturated fatty acids than the meat of HW lambs. In conclusion, under the conditions of the present study, a low body weight at birth increased the deposition of fat in carcass and non-carcass components during the fattening period of lambs, thus reducing animal performance and worsening the nutritional indexes of the meat. Accordingly, it seems reasonable to try to identify these animals during early life, to be sold as suckling lambs in the meat market instead of being fattened.

Assessment of the Welfare of Extensively Managed Autochtonous Sheep Breed Vlasicka Zackel using Animal-Based Measurements

In the Balkan region, the state of sheep welfare is little known. In this context, the assessment of sheep welfare is important for the identification of health and behavioral problems that affect these animals, along with the deficiencies present in the environment. The study was conducted during the winter season on a farm of 220 autochthonous breed Vlašićka Zackel sheep reared in extensive systems on the mountain regions of Bosnia and Herzegovina. A total of 65 ewes, aged 2–4 years, were observed. The welfare assessment was performed according to the AWIN protocol for sheep. The authors found the following issues: dry ewes were significantly fat (p<0.001) in regard to pregnant and lactation ewes; 42.11% of pregnant ewes were thin while 31.25% of dry ewes were fat; most of the assessed animals (78.46%) had dry or damp, slightly soiled fleece; 32.31% of animals had lesions on face/muzzle while ocular discharge, respiratory problems, mild mastitis and minor lameness were present in 16.92%, 4.62%, 15.38% and 7.69% sheep, respectively. All animals showed a negative relationship with humans. Using this methodology, the welfare problems in animals may be detected, and thus certain segments in the production cycle may be improved. The on-farm welfare assessment is highly recommended for emphasizing the key points in improving sheep welfare in Balkan countries.

A history of animal welfare science

Human attitudes to animals have changed as non-humans have become more widely incorporated in the category of moral agents who deserve some respect. Parallels between the functioning of humans and non-humans have been made for thousands of years but the idea that the animals that we keep can suffer has spread recently. An improved understanding of motivation, cognition and the complexity of social behaviour in animals has led in the last 30 years to the rapid development of animal welfare science. Early attempts to define welfare referred to individuals being in harmony with nature but the first usable definition incorporated feelings and health as part of attempts to cope with the environment. Others considered that welfare is only about feelings but it is argued that as feelings are mechanisms that have evolved they are a part of welfare rather than all of it. Most reviews of welfare now start with listing the needs of the animal, including needs to show certain behaviours. This approach has used sophisticated studies of what is important to animals and has replaced the earlier general guidelines described as freedoms. Many measures of welfare are now used and indicate how good or how poor the welfare is. Naturalness is not a part of the definition of welfare but explains why some needs exist. In recent years, welfare has become established as one of various criteria used to decide on whether a system is sustainable because members of the public will not accept systems that cause poor welfare. The study of welfare has become part of the scientific basis upon which important political decisions are made.